The present invention relates generally to hydroentangled (spunlaced) nonwoven fabrics, and more particularly to a hydroentangled composite nonwoven fabric formed from a synthetic fiber web and a cellulosic fiber web, which webs are integrated so that the cellulosic fibers become integrated with the synthetic fiber structure. Integration can be effected on a three-dimensional image transfer device to image and pattern the resultant fabric, including formation of apertures. The resultant fabric exhibits excellent strength and absorbency, and is particularly suited for use in medical gowns, and like applications. The fabric is also well-suited for use as an industrial wipe such as in clean rooms and the like in view of low linting characteristics of the fabric.
Nonwoven fabrics have found widespread application by virtue of the versatility afforded by the manner in which the physical characteristics of such fabrics can be selectively engineered. Formation of nonwoven fabrics by hydroentanglement (spunlacing) is particularly advantageous in that the fibers or filaments from which the fabric is formed can be efficiently integrated and oriented as may be desired for a specific application. Blends of different types of fibers can be readily combined by hydroentanglement so that resultant fabrics exhibiting selected physical properties can be fabricated.
Heretofore, nonwoven fabrics formed from blends of synthetic and cellulosic fibers have been known, with such fabrics desirably exhibiting physical properties which are characteristic of the constituent synthetic and cellulosic fibers. Typically, synthetic fibers can be formed into a fabric so that the characteristics such as good abrasion resistance and tensile strength can be provided in the resultant fabric. The use of cellulosic fibers provides such fabrics with desired absorbency and softness.
U.S. Pat. No. 5,459,912, to Oathout, hereby incorporated by reference, discloses patterned, spunlaced fabrics formed from synthetic fibers and wood pulp which are stated as exhibiting good absorbency, and low particle counts. The fabrics are thus suited for use where these characteristics are desirable, such as for use as wipes in clean rooms, wipes for food service, and like applications. However, this patent contemplates integration of wood pulp fibers and synthetic fibers in a dry state, with subsequent hydroentanglement by treatment on one side only. It is believed that this results in significant loss of the wood pulp fibrous material through the loosely bonded synthetic fibers, thus detracting from the efficiency of the manufacturing process.
Because composite nonwoven fabric materials formed from synthetic and cellulosic fibers can provide a combination of desirable physical properties, the present invention is directed to a method of making such a composite nonwoven fabric which facilitates efficient fabric formation by abating loss of cellulosic fibers to the filtrate water during integration by hydroentanglement.
The present invention is directed to a method of making a composite nonwoven fabric which entails integration of a staple length synthetic fiber web with a web of cellulosic fiber material, typically wood pulp. In order to abate loss of cellulosic fiber material during integration by hydroentanglement, the present invention contemplates that the synthetic fiber web is first subjected to hydroentanglement, with the cellulosic fibrous material thereafter integrated, by hydroentangling on a three-dimensional image transfer device, into the partially entangled synthetic fiber web. This formation technique has been found to desirably abate the loss of the cellulosic fibers during the hydroentangling process into the filtrate water employed for hydroentanglement. The resultant fabric exhibits the desired blend of characteristics achieved by use of the synthetic and cellulosic fibers together, with the manufacturing technique of the present invention desirably facilitating efficient and cost-effective formation of the present fabric. Formation on an image transfer device permits imaging and patterning of the fabric, including formation of apertures.
In accordance with the present invention, a method of making a composite nonwoven fabric comprises the steps of providing a synthetic fiber web comprising staple length polymeric fibers. Use of polyester (PET) fibers is presently preferred by virtue of the economy with which such fibers can be manufactured and processed. The present process further comprises hydroentangling the synthetic fiber web to form a partially entangled web. This partial hydroentanglement desirably acts to integrate the staple length synthetic fibers, prior to introduction of the associated cellulosic fibrous material.
The cellulosic fibrous material of the present fabric is introduced by juxtaposing a cellulosic fibrous web with the partially entangled synthetic fiber web. The juxtaposed webs are then hydroentangled on a three-dimensional image transfer device, and subsequently dried to form the present composite nonwoven fabric. Notably, the pre-entanglement of the synthetic fiber web, prior to introduction of the cellulosic fibrous material, has been found to desirably minimize loss of the cellulosic material as the synthetic and cellulosic webs are integrated by hydroentanglement. It is believed that the pre-entangled synthetic fiber web may desirably act to xe2x80x9cfilterxe2x80x9d the cellulosic fibrous material, so as to minimize its loss to the filtrate water. Additionally, pre-entanglement of the synthetic fiber web desirably permits the use of reduced energy input for entangling the synthetic and cellulosic fiber webs, which is also believed to contribute to reduced loss of the cellulosic fibers. It is also believed that the ability to employ reduced energy input for entangling the component webs allows for maintaining the inherent bulk of the composite nonwoven fabric, and thus allowing for improved absorbency with the increase in interstitial volume over a high-pressure hydroentangled nonwoven fabric.